Housing Affordability Index Calculator
Calculate the NAR-style Housing Affordability Index for any market. Enter local median home price, median income, and current rate — see if the median family can afford the median home.
The NAR Housing Affordability Index has three inputs. Here is how each one moves your local index:
How much does each factor need to change to meaningfully improve affordability? Starting HAI: 78
| Scenario | HAI Change | New HAI |
|---|---|---|
| Rate drops 1% | +9 pts | 87 |
| Rate drops 0.5% | +4 pts | 82 |
| Rate rises 0.5% | -4 pts | 74 |
| Rate rises 1% | -7 pts | 71 |
| Income +5% | +4 pts | 82 |
| Income +10% | +8 pts | 86 |
| Price -10% | +9 pts | 87 |
| Price -20% | +20 pts | 98 |
How to Use This Housing Affordability Index Calculator
Enter the Median Home Price for your local market (check Zillow, Redfin, or NAR.Realtor for your metro or county), the Median Household Income for your area (available at Census.gov or BLS.gov), and the current 30-Year Fixed Mortgage Rate. The calculator instantly produces your local HAI score with a plain-English interpretation.
What Data to Use
For the most accurate local result, use county or metro-level data rather than national averages. The US national median home price (~$415,000) and income ($82,000) produce a national HAI that masks wide local variation — San Francisco HAI is around 40 while Pittsburgh's is around 160. The more local your data, the more meaningful your score.
Advanced Features
Use City Comparison to rank up to 3 metros by HAI side by side. Use Sensitivity Analysis to see exactly how much a rate drop, income growth, or price correction would move your HAI. Use Forecasting to model what affordability looks like in 1-5 years under different scenarios.
The Housing Affordability Index Formula
Qualifying Income = Monthly P&I Payment x 12 / 0.25
Monthly P&I = Loan x [r(1+r)^360] / [(1+r)^360 - 1]
Where: Loan = Home Price x 0.80 (20% down assumed)
r = Monthly rate (annual rate / 12)
HAI = 100: Median family exactly qualifies
HAI > 100: More income than needed (affordable)
HAI < 100: Less income than needed (unaffordable)
The 25% qualifying ratio is a NAR convention — it represents the share of gross income allocated to principal and interest. Modern lenders may use 28-30% for PITI (including taxes and insurance), or 36-43% total DTI. Using 25% makes the HAI slightly conservative — the real threshold most families can reach is closer to 31% of income for total housing costs.
Example: Three Markets at the Same Rate
HAI Comparison at 6.75% — Three US Metro Markets
| Pittsburgh, PA | Austin, TX | San Jose, CA | |
| Median Home Price | $225,000 | $475,000 | $1,450,000 |
| Median Income | $68,000 | $82,000 | $132,000 |
| Qualifying Income Needed | $46,800 | $98,800 | $301,500 |
| Monthly P&I Payment | $1,170 | $2,470 | $7,538 |
| HAI Score | 145 | 83 | 44 |
| Verdict | Affordable | Stretched | Severely Unaffordable |
Pittsburgh's HAI of 145 means the median family earns 45% more than needed — a healthy, accessible market. Austin's 83 means families are stretched; a 1% rate drop or 15% price correction would restore affordability. San Jose's 44 means the median family earns less than half what is needed — only high-income earners can participate in that market.